This invention relates to air blower assemblies, and more particularly, to a device for reducing the power requirements of blower assemblies through air flow reduction. The device of the invention is useful for increasing the operating efficiency of air blower assemblies used in commercial heating and cooling systems by controlling the air volume output.
The blower unloading or air volume control of this invention is particularly useful in controlling the power or energy requirements to drive the impeller or fan wheel of air blower assemblies. The control device of the invention provides effective and aerodynamic control of the air volume intake through the air blower assembly over a full range of operation to thereby control and unload the input power requirements of the blower impeller or fan wheel motor.
The aerodynamic air volume control device of the invention is further useful in effectively and efficiently directing the airflow into a blower assembly to reduce the air turbulence and resultant noise propagation usually associated with such assemblies and, particularly, with those utilizing air volume control devices.
The control device of this invention further provides air volume control directly at the air intake funnel from within the blower assembly cavity to thereby provide an effective and efficient means to regulate the air volume throughput over a full range of intake requirements including the total shut off of air intake to the fan wheel. And, the blower unloading device of the invention provides an air volume intake control device easily adaptable for use with common air blower assemblies.
In the past, various devices have been proposed and utilized to control air volume intake and blower assembly horse power requirements in commerical building environmental control systems. One such device utilizes a plurality of rotatable or pivotable vanes disposed across the entrance section of the blower inlet and which open for full airflow and alternatively close to limit air flow dependent upon the air volume requirement of the building's environmental system. Another control device utilizes a drum assembly that is movable about the outer periphery of the blower impeller assembly to, thereby, control the blower air volume output. Yet, other control devices are operative through the inlet and outlet portions of the blower assembly but which alter and disturb the desired smooth airflow therethrough.
These prior art devices have inherent limitations and difficulties associated with their respective structures and operations. For example, these air volume control devices are generally ineffective at low volume requirements and their respective minimum flow limits have been found difficult to reduce below 20 percent of full volume output. Another problem, particularly with the drum assembly control devices is their low energy efficiencies at common operating conditions. And, although the inlet vane type control systems are generally more energy efficient, they require complex and costly structural designs which aerodynamically interfere with the desired smooth airflow through the inlet funnel.
Another major problem associated with prior art control devices is the generation of noise which requires the costly addition of structural elements to the blower assembly itself or to the building structure if noise is to be suppressed. System noise is produced by the incoming airflow directed against the inlet vanes, for example, as well as the interior blower assembly surfaces, which cause air turbulence in the blower assembly and harmonic vibrations of the blower structural elements. The prior art control devices, therefore, generally have design configurations which create further air turbulence and exacerbate noise propagation.
Despite the need for an effective and efficient air volume control device usable with standard blower assemblies for commercial air heating and cooling systems, and which overcomes these prior art difficulties and limitations, none insofar as is known has been proposed or developed.
Accordingly, it is an object of the present invention to provide a blower unloading device which effectively and efficiently controls the air output volume of a blower assembly over its total operating range, while at the same time substantially reducing the blower's energy consumption. It is a further object of this inveniton to provide a device which is particularly effective at controlling low vlume air flow. It is another object of this invention to provide a device capable of effectively sealing the inlet funnel of the blower to completely shut off air intake.
A further object of this invention is to provide a device which is constructed and arranged to control noise propagation over a broad range of operating conditions. It is also an object of this invention to provide a control device having a structural configuration which reduces air turbulence in the blower assembly throughout its total range of operation.
It is also an object of the present invention to provide a device which fulfills the above-mentioned objects within standard blower design parameters commonly used in the industry.